Circuit arrangement comprising at least one switch for the control of at least one lead



Dec. 8, 1953 L. H. JONKER CIRCUIT ARRANGEMENT COMPRISING AT LEAST ONE SWIT %,662,176 FOR THE CONTROL OF AT '/LEAST om: LEAD Filed April 6, 1948 16% 1&6

m/GGER r 20 Z F l 1] U, INVENTOR.

" l- II Patented cc. 8, 1953 CKRCUET ARRANGEMENT COMPRISING AT LEAST ONE SWITCH FOR THE CONTRO DE AT LEAST ONE LEAD Johan Lodewijk Hendrik Jonker, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn., as

trustee Application March 6, 1948, Serial No. l3,474

Claims priority, application Netherlands April 21, 1947 9 Claims. (01; 25027) The invention relates to a circuit-arrangement comprising at least one switch for the control of at least one lead. It has for its object to construct such circu t-arrangements, so as to be formed entirely by electronic means.

The circuit-arrangement according to the invention exhibits the feature that the switch included in the lead is constituted by a control path arranged in a d scharge tube between two secondary-emission collecting electrodes to which a direct voltage is fed by direct coupling means, this control path being made conductive upon impingement of the electrons from the cathode of the discharge tube on the secondary emission coll cting electrodes.

In order that the invention may be more clearly understood and readily carried into effect, it will now be described more fully with reference to the accompanying drawing, in which several embodiments are shown by way of example.

In the drawing:

Fig. 1 is a schematic diagram of one preferred embodiment of a switching system in accordance with the invention.

Fig. 2 is a curve explanatory of a feature of the invention.

Fig. 3 is a schematic diagram of another pre- 'ferred embodiment of a switching system in accordance with the invention.

Fig. 4 shows a portion of the electrode structure of a cathode-ray switching tube in accordance with the invention.

Fig. 5 shows a portion of the electrode structure of another cathode-ray switching tube in accordance with the invention.

Fig. 1 shows a circuit-arrangement for simultaneously closing and opening two leads, for example, the two-wire lead of a telephony connection.

Connected between the lead sections la and lb and between the lead sections 2a and 2b are control paths 3 and 4 respectively. These control paths are formed by the spaces between two collecting electrodes 5 and 6 and 5a and Go respectively, which exhibit secondary-emission properties and which are included in a discharge tube (not shown) comprising a cathode l and several grid-like electrodes 8 and 8a, 9 and 9a (diagrammatically shown), the electrodes 8 and 811, as well as the electrodes 9 and So being not only electrically interconnected, but also mechanically integral with one another.

The collecting electrodes are intercoupled for direct current by means of resistances 10, II and la, Ha to the positive terminal of a battery 12,

'2 the negative terminal of which is connected to the cathode 7.

If suitably chosen voltages are fed to the said grid-like electrodes, the electrodes 5, 5a, 5 and 6a are struck by anelectron stream emanating from the cathode l.

If an alternating voltage, for example speech signals are fed to the terminals l3a and l3b, this alternating voltage is set up, through blocking condensers I 4a and I 4b, across the collecting electrodes 5 and 5a, the blocking condensers serv ng only to prevent the direct voltage of the battery I 2 from being set up across the lead sections.

If, for example, the potential of the electrode 5 is increased and hence that of the electrode 5a is reduced, secondary electrons will travel from the electrode 6 to the electrode 5, whereas with the control path A secondary electrons flow from the electrode 5a to the electrode 6a. Thus a connection between the lead sections la and lb and 2a and 2b respectively is established.

It may be observed that the two electrodes 5 and 6, and 5a and Ba respectively should be connected, preferably through res stances Ill H, Illa and I l a of the same value to the same direct voltage, in order to prevent one of the electrodes from always having a higher potential than the other which would only enable a flow of secondary electrons in one direction. In order to avoid distortion of the voltage to be transmit ted, it is furthermore desirable that the secondary-emission characteristic curves of the two collecting electrodes of a control path should be substantially similar.

This means that under fully identical conditions the secondary-emission coeflicient, i. e. the number of dislodged secondary electrons per incident electron, is equal .for'the two electrodes.

The circuit-arrangement shown in Fig. l fur ther comprises between each control'path and the cathode an additional grid-like electrode [5a and i511 respectively, which are connected through resistances [6a and I 6b to the positive terminal of the battery iii.

The position of such an electrode and the voltage fed thereto are chosen to be such that if, for example the collecting electrodes 5 and 6 have the same potential and the strength of the flow to each of the electrodes is identical, the current strength to the electrode 15a, due to the secondary emission, is equal to the overall current striking the electrodes.

If the impedance of the control path is increased, for example owing to the presence of space charge, a reduction in impedance of the In Fig. 2 curve I denotes the relationship between the secondary-emission current strength to or from the collecting electrode 6 in milliamperes and the voltage difference between the electrodes '5 and in volts in the absence of the electrode [5a.

Curve 2 shows the same relationship in the presence of the electrode l5a and curve 3 shows the relationship between the current strength to said electrode l5a in milliamperes and the voltage-difierence Vs-Vs.

The curves have been plotted at a cathode current of 2 millamperes the electrodes 5 and 6 exhibiting a voltage of 200 V relative to the cathode.

The curve I plotted without compensation of the incident flow of electrons is of lower slope than the curve 2 which has: been plotted with compensation, so that in the latter case the im pedance of the control path is found to be lower due inter alia to the reduction in space charge.

' The latter curve, moreover, passes through the point of origin and exhibits a; longer straight portion. than the curve I.

duced by known means and is deflected with the use of a pair of deflecting plates as and 2|.

The deflecting plate 2| may be kept at a con- .stant potential for example, and if no voltage is It is apparent from the form of the curve 3 electrode 6 is increased, secondary electrons Will also travel to this electrode, with the result that the number travelling to the electrode [5a is reduced.

For the purpose of disconnecting the circuitarrangement shown in Fig. 1 a sufiiciently' negative voltage is fed, for example, to the controlelectrode 8, 8a. This results in suppression of the flow of electrons, so that the control paths 3 and 4 are out 011. Thus there is only left on the left-hand side of the circuit-arrangement the circuit formed by the lead section In, the blocking condenser Ha, the resistance [0 and la, the blocking condenser [4b and the lead section 2c, since, with cut-on control-paths, these paths exhibit a very high impedance for alternating voltage, owing to the low capacity between the collecting electrodes.

The values of the resistances l0, Illa, It and Ila should preferably be high, since, with conductive control paths, these resistances entail an additional loss.

It is obvious that for the control of only one lead it is sufiicient to insert a single control path in this lead.

Fig. 3 shows a circuit-arrangement for the control of at least one of a plurality of leads. A dischar e tube (not shown) constructed in the form of a cathode-ray tube comprises a number of pairs of collecting electrodes which exhibit secondary-emission properties, for example, lSa and [51), each pair of which forms a control path IT. The resistance It by which these electrodes are connected to the positive terminal of a voltage source are equal, at least in pairs, but for the sake of simplicity all of them may be chosen to be identical. Again, grid-like electrodes corresponding to the electrodes I50. and I5!) of Fig. 1 may be arranged in front of the control paths, but they are not shown here.

;The control of the control paths is efiectedby means of a cathode-ray beam [9. which is profed to the electrode 29, the beam thus strikes a collecting electrode 22.

If it is desired, for example, to establish a connection between the lead sections 23a and 231), which may be connected through blocking condensers to the electrodes of the associated control path, a voltage is applied to the deflecting plate 20 such that the beam strikes the two electrodes of this control path.

A circuit-arrangement of this kind is parposes in an automatic telephony system, conversation being generally exchanged through two leads and a third lead being usually provided for testing and signalling purposes. in order to. enable simultaneous control of three leads, use is made of a cathode-ray tube with flat beam section. In Fig. 3 the beam extends a certain distance at right angles to the plane of the drawing, the three control paths required to be controlled together being arranged in succession in a direction. at right angles to the plane of the drawing, so that with a given deflection oi the beam, the electrodes of these control paths are struck by the beam simultaneously.

Instead of utilizing a flat beam, use may be made of a cathode three separate parts of which have each the function of a cathode, so that viewed in a direction at right angles to the plane of the drawing, three separate beams are produced, each of the beams striking one of the pairs of collecting electrodes.

If the circuit-arrangement is used for the control of one of'a plurality of leads all of which have one lead section in common, this section may be connected to an electrode having the frustro-conical shape designated 42 in Fig. 4, the collecting electrodes 43 connected to the other lead sections being arranged at the circumference and forming, together with the collecting electrode 52, a number of control paths corresponding to the number of leads.

According to a preferred form of circuit-arrangement according to the invention, in order to prevent one or more undesired control paths from becoming conductive during the variation of the deflecting voltage, it is advisable to provide means by which the cathode-ray beam is suppressed as long as it is not directed on to the col lecting electrodes of the desired control path.

This may be effected, for example, with the use of the circuit-arrangement shown in Fig. 3.

It is assumed that, in its position of rest. the cathode-ray beam is directed towards the col lecting electrode 22 and that it is required to be deflected until the control path 24 is made conductive.

The point 25 has supplied to it a voltage increase shown at 28 and adapted to bring about the desired extent of deflection. This voltage increase is supplied to a circuit 3% shown in the form of a block through a network 27, 28 having a differentiating effect and producing a voltage pulse 29. The said circuit, which may be of wellknown design, for example a so-called trigger circuit, produces an output voltage impulse of negative polarity which is shown at El. This impulse is supplied to the control electrode 32 of the cathode-ray tube, so that the beam is tem porarily suppressed.

The occurrence of the voltage impulse 3| is generally slightly delayed relative to the voltage variations 26 and 29. The variation of the defiection voltage across the plate 28 must, however, take place during the occurrence of extinction impulse 3 i. This may be achieved by feeding the voltage variation at point 25 through a delaying network 33 to the deflecting plate 29, the delay being chosen in accordance with the delay occurring in the circuit 32.

As long as the connection established is to be maintained, the voltage at point 25 is kept constant. For the purpose of interruption, the voltage is reduced to its original value, as is indicated at 35. This results in re-occurrence of an impulse voltage 35 at the input of the circuit 3E and hence in re-appearance of a blocking voltage for the cathode-ray beam. Fig. 5 finally is a diagrammatic detail view of a cathode-ray tube comprising magnetic deflecting means, provision being made between the control paths 36 and 3'! and the cathode (not shown) of the tube, of a plate-shaped collecting electrode 38 provided with apertures 353 and it to allow the beam to pass.

Such a precaution is particularly important if the beam is focussed electrostatically and without deflection, that is to say in its position of rest is exactly sharp at the point 41 of the electrode 38, i. e. midway between the two control paths. Owing to the magnetic deflection both towards the one and towards the other control path, the beam, on falling through the aperture 39 or 40, will enter into the control paths in a diffused state and this ensures that both collecting electrodes of a control path are struck, whilst at the same time there is a certain small tolerance in the deflection.

Even if the beam is not focussed electrostatically and even in the case of control paths more remote from the position of rest a! of the oathode-ray beam, provision of the electrode 38 is advantageous, if the beam is focussed approximately at the level of the electrode, because it is already more or less difiuse at the level of the control paths, since the latter is more remote from the cathode.

In addition, the various apertures bring about a keen separation between impingement and non-impingement of the beam on the electrodes of a control path and the adjacent control paths are screened.

If the electrode 38 exhibits a higher potential than the collecting electrodes of the control paths, it may be used in addition for compensating the current strength of the incident flow of primary electrons.

What I claim is:

1. Switching apparatus for controlling current flow in an electrical conductor over which alternating-currents may be transmitted in either direction, said apparatus comprising a cathode-ray tube provided with a pair of secondary-emission collecting electrodes having substantially similar secondary-emission characteristic curves and means including a cathode for pro'ectin a primary electron beam onto said electrodes, 2. pair of resistances of substantially equal value, means to apply a constant potential through the respective resistances to said collecting electrodes, said electrodes effectively constituting the contacts of an electrical switch, and means to interpose said switch in said electrical conductor whereby an alternating-current along said conductor gives rise to a potential difference between said electrodes resulting in a secondary electron flow therebetween in a direction depending on said potential difference, thereby closing said contacts.

2. Switching apparatus for controlling flow in an electrical conductor over which alternatingcurrents may be transmitted in either direction, said apparatus comprising a cathode-ray tube provided with a pair of secondary-emission collecting electrodes having substantially similar secondary-emission characteristic curves, means including a cathode for projecting a primary electron beam onto said collecting electrodes and a supplementary electrode disposed between said cathodic means and said collecting electrodes, a pair of resistances of substantially equal value, means to apply a constant potential through the respective resistances to said collecting electrodes, means to apply a constant potential to said sup-v plementary electrode having a magnitude at which the intensity of primary electron flow to the supplementary electrode is substantially equal to the sum of the intensities of a primary electron fiow to said collecting electrodes, said collecting electrodes effectively constituting the contacts of an electrical switch, and means to interpose said collecting electrodes in said electrical conductor whereby an alternating-current ference, thereby closing said contacts.

3. Switching apparatus for controlling current flow in a pair of electrical conductors over which alternating-currents may be transmitted in either direction, said apparatus comprising a cathoderay tube provided with a beam source including a cathode, two pairs of secondary-emission collecting electrodes having substantially similar secondary emission characteristic curves, each pair being disposed on either side of said cathode, said cathode projecting a primary electron beam onto said collecting electrodes, and a control electrode disposed between said cathode and said collecting electrodes, two pairs of resistances of substantially equal value, means to apply a constant potential through the respective resistances to said collecting electrodes, each pair of collecting electrodes effectively constituting the contacts of an electrical switch, means to interpose each switch in a respective electrical conductor, and means to apply a control potential to said control electrode to control emission between said cathode and said collecting electrodes.

4. Switching apparatus for controlling current flow in a plurality of electrical conductors along each of which alternating-currents may be transmitted in either direction, said apparatus comprising a cathode-ray tube provided with a plurality of pairs of secondary emission collecting electrodes having substantially similar secondary emission characteristic curves, means including a cathode for projecting a primary beam onto said collecting electrodes and a deflecting electrode for deflecting said primary beam, a pair of resistances of substantially equal value associated with each pair of collecting electrodes, means to apply a constant potential through the respective resistances to said collecting electrodes, each pair of said collecting electrodes effectively constituting the contacts of an electrical switch, means to interpose each switch in a respective electrical conductor, and means to apply a deflecting potential to said deflecting electrodes to direct said primary beam onto a selected pair of collecting electrodes.

5. Switching apparatus for controlling current flowiniaplurality of electrical conductorshaving a mmmon'terminal, 'overwhichelectrical conductors alternating-currents maybe transmitted in either direction, said apparatus comprising 'a cathode-ray tube provided with a cathode-a plurality of secondary emission collecting electrodes having substantially equa'l secondary emission characteristic curves, a 'Trustro-conical shaped secondary .emiss'ion electrode disposed to form with said other collectingelectrodesa pluralityof collector electrode .pairs, said cathode projecting a primary electron 'beamin -the direction of said collecting electrodes, and a deflecting electrode, a pair ;of resistances of substantially equal value associated with each pair of collectingel'ectrodes, means to apply a constant potential through' the respective resistances'to said collecting electrodes, each pair .of collecting electrodes effectively constituting the contacts of an electrical switch, means to interpose each switch :in a respective electrical conductor, and means to apply a defleeting potential to said deflecting electrode "to direct said primary "beam onto a selected pair ot collecting electrodes.

"6. Switching apparatus, asset forth in claim5, further including means for suppressing said primary .beam during deflection thereof.

"1. Switching apparatus, as set forth in claim 5, wherein said cathode-ray tube further includes a control electrode, and wherein means are 'provided for generating an impulse voltage of neg ative polarity and for apply-ing said impulse voltage to said control electrode.

8.. Switching apparatus, as set forth in claim '7, further including a delay network, an means for applying said deflecting potential to the deflecting electrode through said network.

9. Switching apparatus for controlling the iicw of current in a plurality of electrical conductors, along each of which alternating currents may be transmitted in either direction, said apparatus comprising a cathode-ray tube provided with a. plurality of pairs of secondary emission collecting electrodes having substantially similar secondary emission characteristic curves, means including a cathode for projecting a primary beam onto said collecting electrodes, a plate-shaped electrode interposed between said cathode and said collecting electrodes and having apertures therein permitting impingement of each pair of collecting electrodes by said primary beam, and magnetic deflection-means for deflecting said primary beam, a pair of resistances of substantially equal value associated with each pair of collecting electrodes, means to apply a constant potential through the respective resistance to said collecting electrodes, each pair of said collecting electrodes effectively constituting the contacts of an electrical switch, and means to lnterpose each switch in a respective electrical conductor.

LODEWIJK HENDRIX EONKER.

References 'Gitcd in the file of this patent UNITED STATES PATENTS Number Name Date 2,185,684 Bennett Jan. 2, 19) 2,207,356 Pierce July 1.940 2,215,779 Clavier :et a1. Sept. 24, 1940 2,220,452 Jarvis et al. Nov. 5,, 1940 2,245,174: Ban-ks June .10, 1941 2,257,795 Gray 4 Oct. 7, 19M 2,489,329 Selgin Nov. :29 1949 

